<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    <h2>{{firstName + ' ' + lastName}}</h2>
    <h2>{{firstName}} {{lastName}}</h2>
    <h2>{{getFullName()}}</h2>
    <h2>{{fullName}}</h2>
</div>


<script src="../../js/vue.js"></script>

<script>
    const vue = new Vue({
        el: "#app",
        data: {
            firstName: "Deng",
            lastName: "jian"
        },
        methods: {
            getFullName: function () {
                return this.firstName + ' ' + this.lastName
            }
        },
        computed: {
            fullName: function () {
                return this.firstName + ' ' + this.lastName
            }
        }
    });
</script>
</body>
</html>